Field testing for Fluoride, Arsenic and Total Iron at Nalbari, Assam. Image courtesy, Ishan Gupta
ffem test devices are open source. They are designed for field use. Typically, ffem tests cost much less than a laboratory test, while they are a lot more precise than a field test kit.
A water testing kit with drinking water, and lake and river water monitoring parameters.
Soil test kit for soil macronutrients NPK and pH.
Current test devices are based on colorimetry. The kits use the camera and flash of a smartphone to detect a colour change created by certain specific reagents. The colour change is compared to a series of calibrated colours and a suitably interpolated result is displayed.
The product may sometimes be referred to as Caddisfly, ffem Caddisfly, ffem Water or ffem soil.